Systems of this type are known in the state of the art. There exists a basic need to check filled containers for contamination such as shards of glass or other insoluble forms of organic or inorganic dirt in the product. For this purpose, many different systems are known according to the state of the art. Most of the optical inspection systems are based on the idea of bringing the contamination, such as a glass shard, into several different positions and of comparing several pictures of the container with each other, as a result of which the presence of the glass shard can be detected. These types of systems are known by the collective term “full bottle inspection” (FBI).
To change the position of the foreign body, the containers are put in motion; in some cases they are swirled, and in others they are rotated around the longitudinal axis of the bottle. When such movements are conducted close in time to the detection process, however, it is possible for water, belt lubricant, and occasionally the product itself (in the case of containers which have broken or have leaks) to be sprayed onto the glass guard of the optical sensor, which is usually a camera. The glass guard therefore become dirty.
The constant contamination of the glass guard is a fundamental problem in the process of inspecting containers as described above. The view of the container degrades over the course of time, and the detection quality decreases correspondingly. It is therefore known in the state of the art that the glass guard can be cleaned regularly. When this cleaning is done manually, however, the down times are increased considerably, and the efficiency of the machine is decreased. In the case of automatic cleaning, the effect of the cleaning operation is often unsatisfactory. In certain machines, the optical monitoring system inspects the bottoms of the containers through the glass guard of the camera, which is brought directly underneath the container bottom. Any moisture which drops off the container thus falls directly onto the glass guard, as a result of which, over time, the view becomes impaired and an error can be detected when none actually exists. In practice, this means that at the glass guards must be cleaned at least once very 8 hours of operating time. When bottles break in the machine, the frequency of the cleanings must be increased.
It has also been found that, when, for example, a container bursts in the inspection carousel or near it, the nearby glass guards become dirty. Another contamination factor is derived from the fact that the inspection carousels known according to the state of the art pass below the acceleration carousels in the area where the containers are transferred. These acceleration carousels are used to accelerate the containers by means of rotational movement, for example. In this case, lubricant and dirt from the drive units can fall onto the glass guards. Because abrasion also occurs, dirt can arrive on the glass guard for this reason as well.